NEW ORLEANS - Marine Lt. Leonard Isaaks Jr. was killed on Feb. 20, 1945, during the battle for the Japanese island Iwo Jima. All you really need to know about his death is contained in the painstakingly printed letter found on his body:

Dear Daddy,

Merry Christmas. We wish we could all be together. …

Lt. Isaaks' story is one of many thousands in the National WWII Museum, a whopping 70,000-square-foot repository of America's collective memory of World War II. Visiting the museum is an intellectually and emotionally walloping passage through a world at bloody, no-quarter war that took 65 million lives and reshaped politics and culture in ways we are still only beginning to understand.

Much more than a bullets-and-bayonets showcase - though there are plenty of those, too - it's a riveting tale of terror and bravery, blood and gore, homicide and heroism, starring our parents and grandparents.

They narrate it themselves, through letters they wrote home at the time and oral histories they gave later. Sometimes their horror is wide-eyed: A soldier remembers huddling in a foxhole one long frozen night during the Battle of the Bulge in December 1944, listening to a terribly wounded comrade cry, over and over, "Mother, mother, help" until silenced by a burst of machine-gun fire: "That beseeching plea on that clear, cold Christmas night will remain with me for the rest of my life."

Other times it is disconcertingly matter-of-fact. "We finally hit the beach," recalls a Marine of the 1944 invasion of Japanese-held Peleliu, "but we went through a whole lot of legs, arms and heads."

The museum is a seamless blend of objects and narratives, the latter supplied not only through the usual placards but oral histories and short films that can be seen on video consoles scattered through the exhibits. Sometimes it is technologically dazzling - in the four-dimensional film "Beyond All Boundaries," shown hourly, soapy "snowflakes" fall from the ceiling during scenes of the Battle of the Bulge and electrically-wired seats rumble like engines as you watch a segment on bomber missions - but it never lets anything get in the way of story-telling.

Sometime the stories need no elaboration from the photos of men with muddy, bloody faces and haunted eyes. Others emerge in their words. Stories emerge from men with muddy, bloody faces and haunted, like those of an emaciated American survivor of the Bataan Death March: "It was something out of, what is it, Dante's 'Inferno'? It was hell." Some emerge in grisly chapters: The junior Marine officer who wrote his family from the Pacific that he commanded 46 men, but refused to get to know any of them, because he didn't want to order a friend to his death; the junior Army officer at Normandy who saw 23 of his 24 men killed in a single 25-yard stretch of sand.

Even the most mundane artifact in the display cases has a tale to tell. The wristwatch that Pvt. Harold Baumgartner wore as he stormed ashore at Omaha Beach during the D-Day invasion of France looks quite ordinary, until you learn that it was practically the only thing on his body that was not shot to pieces - he was wounded five times in two days. A photo of five grinning sailors loses its good cheer when you realize that they were the brothers known as the Fighting Sullivans, all killed in a single attack by a Japanese submarine in 1942.

The war's brutality is not merely implied; it's shockingly, appallingly explicit. Photos of burnt and battered corpses are plentiful. There are shots of Japanese soldiers using live Chinese prisoners for bayonet practice and the charred dead left in the rubble of the German city of Dresden after a massive Allied firebombing raid. Mountains of starved, gassed victims of Nazi concentration camps are underlined with the simple words of an American paratrooper who found them: "Now I know why I am here."

A few sections of the museum are posted with warnings that they may be inappropriate for children, but the truth is that there's hardly any part of it that doesn't contain disturbing material. Practically nobody gets through it without some tears, Nick Mueller, the former University of New Orleans historian who's the museum's president and CEO, makes no apologies for its blunt approach.

"It was a brutal war," he says. "People need to remember that this was a war that was a fight to the finish - for our nation, our democracy, for civilization itself. . Sixty-five million people died in that war, and two-thirds were civilians. That's a big number, a horrific loss of life. Over 400,000 Americans died, many more were maimed and wounded. We don't want to glorify that. War isn't pretty."

But the museum is not without its lighter moments, some ruefully so. A bombardier who flew on Gen. Jimmy Doolittle's famous 1942 air raid on Tokyo - the first American attack on Japanese soil of the war, after a long string of military catastrophes - recounts bailing out of his shot-up plane over China, only to land in a rice paddy generously fertilized with human excrement. "It sounds funny now," he indignantly declares, "but it ain't funny out there, I can tell you."

A newspaper comic strip published at the end of the war helpfully offers tips to Americans on how to tell apart their Chinese allies and their Japanese enemies: "Make them say lalapalooza." A woman smiles wryly as she remembers her soldier husband's vexed reaction at learning she had liberated herself from keeping house to work in a military factory. The gear their commanders issued soldiers before the D-Day invasion, including packages of Ultrex Platinum condoms ("troops found these useful in keeping sand and water out of rifle barrels," an information panel observes with a straight face) and a tourism booklet titled "Pocket Guide To France." A Rupert, one of the large dolls dressed like paratroopers and armed with firecrackers dropped into France in an attempt to confuse the German troops about the direction of the Allied attack. And the message to his girlfriend one American soldier painted on his empty tent in a British meadow before heading to his Normandy-bound ship: "Sorry Jean Had To Go. Johnny."

The vast collection of material on D-Day even extends into what might termed alternative history - a handwritten speech that Allied commander Dwight Eisenhower carried in his pocket in case the Normandy invasion was thrown back into the sea: "If any blame or fault attaches to the attempt it is mine alone." Fortunately, it never had to be delivered.

The enormous amount of D-Day content is a remnant of the museum's origins. It was founded by the late University of New Orleans historian Stephen Ambrose, who while researching a book on the invasion learned that the thousands of landing craft that carried troops and tanks ashore that day had been designed and constructed by New Orleans shipbuilder Andrew Higgins. (Later, when Eisenhower was president, he declared that "Higgins is the man who won the war for us.")

"In 1990, over way too many drinks in Steve's backyard, we were talking about how nobody knew what an important role New Orleans had played in D-Day," Mueller remembers. "And at the same time, Steve was thinking he needed a place to showcase all the oral histories and photos and other mementos he had collected for the book, and I had been assigned a project to open a research park on the lakefront here. And it all came together.

"Steve said, 'We'll have to raise a lot of money. It'll cost $1 million.' I said, 'You're crazy, it'll be $4 million.' And just $30 million and 10 years later, we opened the D-Day Museum for business."

Almost instantly, though, Ambrose and Mueller realized they'd made a mistake. The museum was flooded with visiting World War II vets who loved it but had done their fighting elsewhere beside Normandy and wondered why their stories couldn't be told. And a couple of them, U.S. Senators Ted Stevens (R-Alaska, who served in the war's China-Burma-India theater) and Daniel Inouye (D-Hawaii, who lost an arm fighting in Italy), were in a position to help get government money for a broader museum.

The museum has already added a vast, labyrinthine section on the island-hopping war in the Pacific, including a copy of President Roosevelt's address to Congress the day after the Japanese sneak attack on Pearl Harbor, complete with his handwritten corrections: ". a date which will live in world history infamy ."

And the museum is two years from the end of a $300 million expansion that will double the floor space for exhibits and add two more buildings to the existing three. They'll house major exhibits on the war in Africa, on the Asian mainland and the battle for Berlin, as well as more big-ticket weaponry like tanks, planes and even a submarine in which visitors can take part in a simulated attack on a Japanese convoy. (Several tanks, half-tracks and other armored vehicles already dot the floor of one pavilion, while combat aircraft are suspended from the ceiling.)

The World War II generation, which initially fueled the museum's popularity, is steadily vanishing; even the era's teenagers are now in their 80s. But that hasn't dimmed the museum's attraction: April, with nearly 45,000 visitors, was its busiest month ever. Mueller doesn't believe that's going to change, because World War II isn't really history: Its effects on American attitudes on race and gender and the political boundaries it redrew are still evolving.

"Every day in the newspaper, you see why World War II is still relevant," he says. "We're still trying to deal with people of different cultures and races and religions around the world. The 9/11 attacks brought that to the forefront. The Arab Spring brought it back up - the end of the monarchies in the Middle East is the end of a process that began in 1945. World War II is still with us today, and it's going to be for a long, long time."

ADMISSION: $21; $18 ages 65-79; $12 (ages 5-12 and 80 and up and students and active or retired military and spouse with ID); free for military in uniform. Show-only and museum-and-show tickets available $5-$23. Parking $6 at adjacent visitor lot on Camp Street.

DINING & ENTERTAINMENT: The main museum building contains a counter-service cafe with oversized hot dogs, sandwiches and what it bills as "homemade" Spam. Unless you're ravenously hungry and in a hurry, save your appetite for the full-scale restaurant, The American Sector, across Andrew Higgins Drive. The restaurant has a huge bar flanked by banquettes graced with glamorous black-and-white portraits of wartime USO stars. The gourmet dishes, including lobster pot pie, are devised by chef John Besh. The restaurant is in the building that houses the theater for the Tom Hanks produced-and-narrated 4-D film "Beyond All Boundaries" (screened 10 a.m.-4 p.m. daily, 10 a.m.-5 p.m. Fridays and Saturdays; tickets range from $5 for kids 4 and under to $14).

In this same annex is The Stage Door Canteen with 1940s-style live entertainment and a bountiful, tasty, buffet prepared by Besh and his staff. Entertainment includes a lunchtime revue of popular World War II tunes and patriotic songs by young women impersonating the Andrews Sisters and other USO entertainers of the era; a Sunday buffet brunch and show; and the Friday-Saturday dinner show "Jump Jive and Wail! The Music of Louis Prima," playing through Nov. 24. Tickets $30 to $60. Information: 504-528-1943 or http://www.stagedoorcanteen.org.

NAVAL STATION NORFOLK — The Navy on Saturday commissioned the USS John Warner, adding a 12th Virginia-class submarine to the fleet and celebrating the legacy of its namesake, the retired senator who was hailed as a statesman.